Elemental Energy (EEN) includes several new Elemental Heroes as well as new support cards for the XYZ Monsters. It also features the Queen's, King's and Jack's Knights. A new set of cards introduced in this set are the "Dark World" monsters, which have powerful effects that activate when they are discarded from the hand. Memorable cards from this set include "Goldd, Wu-Lord of Dark World," "Hydrogeddon" and "Sillva, Warlord of Dark World."